1. Technical Field
The present invention relates to a table cutting machine adapted to move a cutting machine body provided with, for example, a round grind stone or a rotary blade such as saw tooth downward for carrying out a cutting operation or the like to a cut material fixed on a table.
2. Description of the Related Art
In the table cutting machine having a configuration in which a substantially upper half range of the periphery of the rotary blade is covered with a fixed cover (blade case) and a substantially lower half range of the peripheral thereof is covered with a movable cover which employs an open-close system has been disclosed. An electric motor as a drive source is arranged on the rear side of the fixed cover. The electric motor causes a spindle projecting into the fixed cover to rotate. The rotary blade is mounted to the spindle. The movable cover is gradually opened in association with the downward movement of the cutting machine body and, meanwhile, a lower portion of the rotary blade is gradually exposed and this exposed portion gradually cut into the cut material. Therefore, a maximum range of the rotary blade which is able to cut into the cut material is limited to a range exposed downward from the fixed cover in a state in which the movable cover is fully opened.
Yet, a larger cutting depth is required for some special cutting operations. In a case of cutting a so-called crown-mold material, which is a cut material used mainly as a house-building material and has widthwise ends inclined in the opposite directions from each other in terms of the thickness direction, in the widthwise oblique direction for example, since both the oblique end surfaces at the widthwise ends need to be cut at an precise angle, the cut material generally is leaned obliquely between a table and a positioning fence, is fixedly positioned, and is brought into abutment at the inclined end surfaces thereof at the widthwise ends with the upper surface of the table and a positioning surface of the fence respectively in a surface abutment state and, in this state, the table is rotated, and the rotary blade is advanced so as to cut into the material obliquely in terms of the widthwise direction, so that an angular cutting is achieved.
In order to carry out the special cutting operation as described above (for example, the cutting operation carried out for a high cut material by placing the same so as to lean obliquely between the table and the positioning fence), various technologies have been disclosed. For example, a lower end portion of the fixed cover in a range on the rear side of the spindle (the center of rotation of the rotary blade) (hereinafter, referred simply as a rear edge of the fixed cover) is recessed upward to secure a larger cutting depth in the range on the rear side, thereby enabling the above-described special cutting operation.
According to these technologies, as a result of having retracted the rear edge of the fixed cover upward, part of a cutting edge of the rotary blade is not covered completely with the movable cover, and hence a configuration in which the uncovered portion is covered by an additionally provided auxiliary cover. This type of configuration can use a link lever to open and close the auxiliary cover using the upward and downward movement of the cutting machine body or a configuration in which the auxiliary cover is turned in the closing direction by its own weight, is brought into abutment with the upper surface of the cutting material, and is relatively opened by the downward movement of the cutting machine body is employed as the opening and closing operations of the auxiliary cover employed.
However, according to the opening and closing structure of the auxiliary cover in the related art as described above, a technology for reliably locking the auxiliary cover at the closed position in a state in which the cutting machine body is positioned at an upper waiting position has not been proposed.
Further, a lever of a single lever type having one grip has been previously proposed. However, with the fixing lever of the single lever type, the grip is hidden behind the supporting arm portion and hence is hardly visible from the user. Therefore, there is a problem of deterioration of operability in that the user needs to operate blindly and thus difficult and dangerous to reach the lever. Also, fixing lever of a triple lever type having three grips coupled in the radial direction at spaces of 120° with respect to each other has been proposed. In this case, however, there is a case in which one of the grips on the lower side abuts against a floor or the ground on which the cutting machine is installed and hence rotational operation is disabled. Therefore, the respective grips are shortened in order to avoid the abutment as described above, which causes a problem of deterioration of operability.
Thus, there is a need in the art for a configuration in which the range of the rotary blade which is not covered by the movable cover from the range exposed from the fixed cover is covered by the auxiliary cover and the auxiliary cover is reliably locked at the closed position so as not to be operated carelessly to the opening position when the cutting machine body is in a waiting position.